In mode lines+markers, if a line is specified with color from a numerical vector the plot silently fails. This happens regardless of whether I'm trying to display it in a notebook or write a file. Here's an example:

And here's a copy-able version of the relevant code:

import plotly.graph_objs as go
import numpy as np

x, y, z, c = np.random.random_sample((4, 10))
go.FigureWidget(data=[
    go.Scatter3d(x=x, y=y, z=z,
                 line=go.scatter3d.Line(color=c))
])